You are in the forested plains of South America, 70 million years ago.

A low, thrumming tremor that traveled up through the soles of your feet, shaking the dew from the prehistoric ferns. Then, the canopy ahead simply disappeared.

It didn't break through the trees—it became the trees. A neck, roughly 37 feet of corded muscle and bone, arched above the tree line, bringing with it a head that moved with surprising grace. Its hide was mottled, perhaps grey and olive, a massive, muscular wall of flesh.

The Dreadnoughtus halted. Its immense body, the size of a Boeing 737 plane, settled with a massive thud that felt like a localized quake. It didn’t look at you. To this creature, you were barely the size of an insect. It was a 65-ton titan, a colossus that feared nothing in its Cretaceous world.